Stromatolites are formed under algal mats of blue-green algae(Cyanobacteria) because lime particles are cemented together in hard, often laminated crusts. The primitive cyanobacteria had no nucleus and further only contained chloroplasts. It is one of the oldest forms of life that is known. There are specimens known from the middle Proterozoic (1.8 billion years ago). In the Proterozoicmassive amounts of limestone has been formed this way. Today, stromatolites still occur at some places on Earth.

Example of a fossil stromatolite

Do you have additional information for this article? Please contact the Fossiel.net Team.